Anybody know the likely cause

[DKgrowWeed]

I am about 7 weeks into the seedling/veg cycle of Girl Scout Cookies and will be starting flowering in 3 weeks. I’ve been adding Fox Farm Big Bloom, Fox Farm Grow Big and General Hydroponics CaliMagic to each watering about every 3 days. Soil is dry and plants on verge of wilting so I know I’m not overwatering. Why the discoloration on the leaves? I just raised my lights again as the tops got to with 10”. Using LED Spider Farmer G5000 light at 50% dimmer setting per recommendations. Any help is appreciated…
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[Rwise]

Have you checked the PH?

 

[DKgrowWeed]

Not yet, I will do that tomorrow

 

[Bluey]

They look great!

Growing pains with a minor magnesium deficiency.

 

[greenmonster714]

1/2tsp of epsom salts in a gal will make the yellowing in the ribs of the leaf go away.

 

[Bluey]

If the soil is still good. Id be pH'ing the inputs just to ensure its not a Mg lockout, which is most often the case.

 

[DKgrowWeed]

Thanks Bluey

 

[DKgrowWeed]

I checked the ph at roots and read 8. I checked the water and it was 8.1. Once I added nutrients the ph dropped to 6.2 so I added some ph down and watered for the next 4 feedings at 5.5. Seems to have helped. Went to flower on 10/10 and changed lights from 18 hours at 50% to 12 hours at 90% and got some curling at one of the new leaf sites on one of the plants. Also am noticing more light color on the leaves. I haven’t tried the epsom salts yet as I just saw the post. Added some photos.

 

[Bluey]

Back your lights off a bit until you sort the nutrient issue.

Strong LEDs at the plants limit will bring out all sorts of nutrient issues.

A slightly higher pH shouldn't be an issue that causes a Mg deficiency so add a small amount of epsom salts as greenmonster recommended